The Internet Protocol Multimedia Subsystem (“IMS”) is an architectural framework for delivering Internet Protocol (“IP”) multimedia to mobile users, such as users of smart phones or tablet computers. An IMS core network (“IMS network”) permits wireless and wireline devices to access multimedia, messaging, and voice applications and services. IMS standards and specifications have been promulgated by the 3rd Generation Partnership Project (“3GPP”™). To allow the IMS network to be integrated with Internet resources, the 3GPP specifications use Internet Engineering Task Force protocols within the IMS network, such as Session Initiation Protocol (“SIP”) and Diameter. SIP is a signaling protocol used for creating, modifying and terminating two-party or multiparty sessions consisting of one or several media streams. A mobile device registers its IP address with a SIP registrar server within an IMS network by generating and sending a SIP request message with a “REGISTER” method token. Once registered, a mobile device may subsequently establish multimedia sessions via the IMS network.
An IMS client (or IMS stack) software component on a mobile device allows one or more applications on the mobile device to register for various application services that are available on the IMS network, such as Voice over LTE (VoLTE), Rich Communication Services (RCS), Short Message Service over Internet Protocol (SMS over IP), and Presence. If the registration is successful, the mobile device application may then take advantage of the functionality offered by the application service to which it is registered. If the registration is unsuccessful, however, then the application will be unable to take advantage of the offered functionality.
The drawings have not been drawn to scale. Similarly, some components and/or operations may be separated into different blocks or combined into a single block for the purposes of discussion of some of the embodiments of the present invention. Moreover, while the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.